5024WLMi random reboot problem

I'm having small problems with my laptop randomly rebooting/crashing. This happens both when AC is connected and when it's running of the battery. From the reason that it does this even when running of the battery I can exclude the option that it would be my GPU overclock that is causing it(as Powerplay is on). In my opinion I can also exclude the possibility that it's rebooting/crashing because of my undervolting because I've already raised the volts that I initially found as stabel with 0.05V and 0.075V. I'm suspecting that it might be my HDD that is overheating(It's a Samsung HM100JC 5400RPM 8MB) but I cannot confirm my suspicion yet. This doesn't happen very often though so atm it's only a minor annoyance but I still would want to get it fixed.

Any other ideas what could be causing these reboots/crashes? And if it's the HDD that's causing them, is there a way to confirm this and perhaps fix it(other than returning the laptop)?

Update: I've now watched my HDD temps a little closer and it seems that it's near 55C most of the time, at 55C SMART gives me a warning.

Update2: After playing for a while the HDD temperature seems to have gone up to 60C(!), so I guess I can exclude the option that the system is crashing when HDD's temperature reaches 56C...

 

Update3(Posted a new message to bump this): Seems I managed to crash the system again... twice. In the past the few days the only occasions it has crashed has been when the AC has been disconnected and this time I got a BSOD. It restarted too fast for me to get a chance to read it but after sending the report to Microsoft, this was what they had to say:

I've got no clue why it's doing this. I've raised the voltage to the default level to see if that's the cause but it would be strange if it was, as it would mean that this processors couldn't be undervolted at all. So c'mon guys, help me out here a little. Oh, and the crashes happen always when I'm watching a movie or something else.

 

To see the BSOD message, go to Control Panel->System->Advanced->Startup and Recovery Settings and uncheck "Automatically restart". When you get the BSOD, write down all the info, then restart manually.

Try disabling all overclocking/undervolting on the CPU/GPU/RAM/etc. Also, you might want to run a memory diagnostic tool such as MemTest86/MemTest86+ or Windows Memory Diagnostic to test your RAM.

 

The funny thing is, that it's already unchecked.

I've only undervolted the CPU and overclocked the GPU but the overclock should have no effect as when the AC is disconnected, Powerplay kicks in. I'm trying with the disabling of my undervolting and I'll test Memtest86.